1. Field of the Invention
The present general inventive concept relates to a scanning apparatus, and more particularly, to a two-side scanning apparatus and a method of controlling the same.
2. Description of the Related Art
In general, a two-side scanning apparatus refers to an apparatus that scans one side of a sheet transferred from a sheet loading tray and then automatically reverses the sheet to scan an opposite side of the sheet. Various conventional types of two-side scanning apparatuses have been developed and used. Japanese Pat. No. 2002-087712 discloses an example of a conventional two-side scanning apparatus. The conventional two-side scanning apparatus disclosed in Japanese Pat. No. 2002-087712 will now be described.
FIG. 1 is a cross-sectional view of the conventional two-side scanning apparatus 1 disclosed in Japanese Pat. No. 2002-087712.
Referring to FIG. 1, the conventional two-side scanning apparatus 1 includes a pickup unit 10, a sheet feeding roller 20, a guide unit 30, a sheet discharging unit 40, and a plurality of sheet reversing paths 51, 52, 53, 54, and 55.
The pickup unit 10 includes a pickup roller 12 and a separator roller 13 and picks up sheets that are loaded into a sheet loading tray 11 one by one. The sheet feeding roller 20 includes a drive sheet feeding roller 21 and a passive sheet feeding roller 22 and transfers a sheet that is picked up by the pickup unit 10.
The guide unit 30 includes a white roller 31 that presses a sheet against a sensing surface to be sensed by an image sensor 3 and transfers the sheet. The guide unit 30 further includes first, second, and third pinch rollers 32, 33, and 34 that contact an outer circumferential surface of the white roller 31 and are driven by the white roller 31.
The sheet discharging unit 40 includes a sheet discharging roller 41, a first pressing roller 42 installed on the sheet discharging roller 41 to contact the sheet discharging roller 41, and a second pressing roller 43 installed beneath the sheet discharging roller 41 to be raised and/or lowered with respect to the sheet discharging roller 41. The second pressing roller 43 is raised and/or lowered by a raising and lowering apparatus (not shown) including a cam. If the second pressing roller 43 is raised, the second pressing roller 43 contacts the sheet discharging roller 41 to rotate along with the sheet discharging roller 41. If the second pressing roller 43 is lowered, the second pressing roller 43 does not rotate along with the sheet discharging roller 41.
The plurality of sheet reversing paths 51, 52, 53, 54, and 55 include a first sheet reversing path 51 formed to guide sheets between the sheet feeding roller 20 and the guide unit 30, a second sheet reversing path 52 formed between the sheet feeding roller 20 and the sheet discharging roller 41 and the first pressing roller 42 of the sheet discharging unit 40, a third sheet reversing path 53 formed between the sheet discharging roller 41 and the first pressing roller 42 of the sheet discharging unit 40 and the guide unit 30, a fourth sheet reversing path 54 formed between the guide unit 30 and the sheet discharging roller 41 and the second pressing roller 43 of the sheet discharging unit 40, and a fifth sheet reversing path 55 formed to connect the third sheet reversing path 53 to the fourth sheet reversing path 54.
Additionally, a first guide plate 61 is installed at an intersection between the first and second sheet reversing paths 51 and 52 to pivot therebetween. A second guide plate 62 is installed at an intersection between the second and third sheet reversing paths 52 and 53 to pivot therebetween. A third guide plate 63 is installed at an intersection between the fourth and fifth sheet reversing paths 54 and 55 to pivot therebetween. One of the first through fifth sheet reversing paths 51 through 55 through which sheets are transferred is selected based on a position of each of the first, second, and third guide plates 61, 62, and 63.
A two-side scanning operation of the conventional two-side scanning apparatus 1 will now be described with reference to FIG. 1.
The sheets picked up by the pickup roller 12 from the sheet loading tray 11 are separated by the separator roller 13 one by one and are then transferred to the sheet feeding roller 20. Here, the first, second, and third guide plates 61, 62, and 63 are positioned toward upper positions B, D, and F, respectively. Thus, the sheet transferred by the sheet feeding roller 20 is transferred between the first pressing roller 42 and the sheet discharging roller 41 along the second sheet reversing path 52. Since the sheet discharging roller 41 rotates in a forward direction (i.e., clockwise), the sheet that is disposed between the first pressing roller 42 and the sheet discharging roller 41 is discharged above the sheet discharging tray 44.
If a rear end of the sheet is determined to be positioned between the first pressing roller 42 and the sheet discharging roller 41, the sheet discharging roller 41 stops rotating in the forward direction. Here, the second guide plate 62 is lowered to position C to intersect the second sheet reversing path 52. In this state, the sheet discharging roller 41 rotates in a reverse direction (i.e., counterclockwise) to transfer the sheet to the guide unit 30 through the first sheet reversing path 53. The sheet transferred to the guide unit 30 is guided to the sensing surface to be sensed by the image sensor 3 via the white roller 31 and the first and second pinch rollers 32 and 33. The image sensor 3 then scans one side of the sheet positioned thereon. The scanned sheet is then transferred between the sheet discharging roller 41 and the second pressing roller 43 through the fourth sheet reversing path 54. Since the sheet discharging roller 41 rotates in the reverse direction, the sheet that is disposed between the sheet discharging roller 41 and the second pressing roller 43 is discharged to the sheet discharging tray 44.
When the rear end of the sheet is positioned between the sheet discharging roller 41 and the second pressing roller 43, the sheet discharging roller 41 stops rotating in the reverse direction. Here, the third guide plate 63 is lowered into position E to intersect the fourth sheet reversing path 54. When the sheet discharging roller 41 rotates in the forward direction in this state, the sheet is transferred through the fifth and third sheet reversing paths 55 and 53 to the guide unit 30. When the sheet enters the guide unit 30, the second pressing roller 43 is lowered and is separated from the sheet discharging roller 41. The sheet transferred to the guide unit 30 is then guided to the sensing surface to be sensed by the image sensor 3 via the white roller 31 and the first and second pinch rollers 32 and 33 such that a side of the sheet opposite to the side of the sheet scanned in the previous process faces the image sensor 3. The image sensor 3 then scans the opposite side of the sheet. The sheet, which is completely scanned, is then transferred between the second pressing roller 43 and the sheet discharging roller 41 through the fourth sheet reversing path 54. Here, since the second pressing roller 43 is in a lowered state (i.e., separated from the sheet discharge roller 41), a portion of the sheet protrudes above the sheet discharging tray 44 without contacting the second pressing roller 43. Once the sheet is transferred a predetermined distance, the second pressing roller 43 is raised and the sheet discharging roller 41 rotates in the reverse direction to completely discharge the sheet onto the sheet discharging tray 44.
When two or more sheets are sequentially scanned, both sides of a first sheet are completely scanned, and then the first sheet stops between the second pressing roller 43 and the sheet discharging roller 41. In this state, a second sheet starts to be fed from the sheet load tray 11. In other words, when the first sheet is positioned between the second pressing roller 43 and the sheet discharging roller 41, the pickup unit 10 and the sheet feeding roller 20 operate such that the second sheet is transferred toward the second sheet reversing path 52. Simultaneously, the sheet discharging roller 41 rotates in the forward direction to transfer the first sheet to the guide unit 30 through the fifth and third sheet reversing paths 55 and 53. When a rear end of the second sheet is positioned between the first pressing roller 42 and the sheet discharging roller 41 and a front end of the first sheet goes into the guide unit 30, the second pressing roller 43 is lowered and is separated from the sheet discharge roller 41. When a rear side of the first sheet is completely scanned in this state, the sheet discharging roller 41 rotates in the reverse direction and the second pressing roller 43 is raised. The first sheet, which is completely scanned, is then discharged to the sheet discharging tray 44, and the second sheet is transferred to the guide unit 30 to perform scanning on both sides thereof.
In the conventional two-side scanning apparatus 1 described above, the first through fifth sheet reversing paths 51 through 55 and the first through third guide plates 61 through 63 are installed to guide the transfer of sheets to reverse the sheets for scanning both sides thereof. Additionally, an apparatus to raise and lower the second pressing roller 43 of the discharging unit 40 is required. Thus, the conventional two-side scanning apparatus 1 has a complicated structure. In addition, a plurality of sensors are required to determine positions of the sheets along the first through fifth sheet reversing paths 51 through 55. Thus, a large amount of cost is required to perform a two-side scanning function in the conventional two side scanning apparatus. Additionally, a large installation space is required. As a result, the conventional two-side scanning apparatus 1 is typically large and/or bulky.